In Genesis, the Flood waters prevailed over the Earth for 150 days before receding.
Genesis 7:24 states that the waters prevailed over the Earth for 150 days. The text then describes God causing a wind to pass over the Earth, after which the fountains of the deep and the windows of heaven were closed and the waters began to subside.
This figure is distinct from the forty days and forty nights of rain. Forty days describes the period of intense rainfall, while 150 days describes the period during which the waters remained dominant. The ark's complete voyage lasted longer still, because Noah waited for the water level to fall, the ground to dry, and God's instruction before leaving.
The chronology of the Flood chapters has attracted scholarly discussion because some passages use different day counts and dating patterns. Nevertheless, the specific statement in Genesis 7:24 gives 150 days for the waters prevailing.